Estimate
One standard drink is about 12 oz of 5% beer, 5 oz of 12% wine, or 1.5 oz of 80-proof spirits.
Enter drinks, weight and hours to see an estimate.
This estimate can’t be used as evidence and can’t tell you whether you are impaired. Officers and labs use breath and blood tests, which can differ from any formula.
California BAC limits
| Driver | Limit | Law |
|---|---|---|
| Adults 21 and over | 0.08% | Vehicle Code § 23152(b) |
| Commercial drivers | 0.04% | Vehicle Code § 23152(d) |
| Rideshare and other drivers for hire, with a passenger | 0.04% | Vehicle Code § 23152(e) |
| Under 21 (DMV suspension, “zero tolerance”) | 0.01% | Vehicle Code § 23136 |
| Under 21 (infraction) | 0.05% | Vehicle Code § 23140 |
| Anyone on DUI probation (DMV suspension) | 0.01% | Vehicle Code § 23154 |
Under 0.08% is not a safe harbor
You can be charged with DUI at any BAC if alcohol or drugs impaired your ability to drive (Vehicle Code § 23152(a)). Driving under the influence of drugs, including prescription medication and cannabis, is a separate offense (Vehicle Code § 23152(f)), as is the combined influence of alcohol and drugs (§ 23152(g)).
How the estimate works
The calculator uses the Widmark formula, a decades-old way of estimating peak alcohol concentration from the amount of alcohol, body weight and an average body-water factor, minus a typical elimination rate of about 0.015% per hour. Real people vary widely around these averages. Absorption is slower with food and faster on an empty stomach, and a person’s BAC can keep rising for some time after the last drink.
How BAC is tested in a real case
After a DUI arrest, California’s implied consent law requires a breath or blood test (Vehicle Code § 23612). Breath machines must be calibrated and maintained, blood must be drawn, stored and analyzed correctly, and the timing of the test matters. Those details are often where a DUI defense begins. If you’ve been arrested, keep track of when you ate and drank and talk to Eric before you discuss it with anyone else.
Law cited: Vehicle Code §§ 23136, 23140, 23152. Last reviewed October 2026.
General information, not legal advice. Every case is different.